A standard tire comprises a pair of annular bead wires interconnected by an annular U-section reinforcement, a liner inside this structure, and an elastomeric tread-forming body outside it. The liner is gas tight for standard tubeless use of the tire, and the tread-forming body is vulcanized through the reinforcement with this liner so the entire assembly is essentially one piece.
Such a tire is made according to Austrian patent 383,541 from a prefabricated outer part comprising the tread, belting underlying the tread, and the outer regions of the tire side walls and a prefabricated inner part comprising the liner, bead wires, and radial windings. This inner part is fitted over a cylindrical bladder which is then expanded to push it into the U-section outer part, and then the two parts are bonded together. Subsequently the bladder is relaxed and withdrawn.
This method is some improvement on the prior-art systems using a solid mold core, but still has substantial room for improvement. The prefabrication of the inner and outer parts is a substantial amount of work. In addition the bladder frequently blows up asymmetrically so that the resultant tire is similarly asymmetrical and must be rejected. Furthermore the bladder is subjected to considerable wear and must be replaced often.
In Austrian patent 379,346 a radially reinforced tire inner part is drawn over an inflatable bladder and the core of a prefabricated belt is drawn over it. Then this assembly is covered with the liquid elastomer which hardens to form the onepiece tire. Once again the inflatable bladder is a much abused element that must be replaced often, with the concomitant down time for the machinery and plant.